Unfortunately, prolongation of life in AIDS sufferers may lead to a higher incidence of AIDS-related cognitive deficits. It is, therefore, extremely important to develop an animal model of human AIDS-related cognitive impairment. A neurotropic variant of SIV (SIVsmmFGb) is being tested in pigtail macaques that have been trained on a battery of cognitive tasks. The battery included a Motor Coordination test, the Spatial Reversal test, the Delayed Non-Matching to Sample, 120-second delay (DNMS-120s), and the Delayed Recognition Test, Spatial Condition (DRST-Spatial). Infected (n=6) and Control (n=3) monkeys displayed equivalent performance on the Motor Coordination Test and the DNMS-120s test, but displayed deficits in performance of the DRST-Spatial and Spatial Reversal tests. In the latter two tests, the deficits in performance were expressed as significantly reduced rates of improvement of performance over successive repetitions of the battery. The fact that performanc e of infected and non-infected monkeys was equivalent on the Motor Coordination test and on the DNMS-120s task indicates that deficits on the other two tasks were due to specific cognitive impairments rather than to reduced levels of motivation. The SIV-infected pigtail macaque may provide the needed model for future studies of possible treatments of AIDS-related dementias. FUNDING NIH / NIA $60,000 05/01/97 - 04/30/98 PUBLICATIONS None P51RR00165-38 1/1/98 12/31/98 Yerkes Regional Primate Research Center